Over the years, there has been much speculation about who killed JonBenét Ramsey in 1996.

The list of possible suspects in one of the most sensational murder cases of all time — when the six-year-old beauty pageant contestant was found dead in the basement of her family’s home in Boulder, Colorado, on Christmas morning — is long.

The list includes everyone from her parents, John and Patsy Ramsey, to her then 9-year-old brother Burke, to convicted pedophile Gary Oliva and former teacher John Mark Kerr, who confessed to killing her in 2006 but was never charged. in connection with her death.

But one potential suspect stands out, at least to her father: a masked intruder who snuck into the home of a 12-year-old girl in Boulder, Colorado, nine months after JonBenét’s murder. The suspect raped the girl and then ran away when the child’s mother scared him off.

“To me, it could easily have been the same person,” Ramsey tells PEOPLE in an exclusive interview.

But, John adds, “The police dismissed it as, ‘No, it’s not the same.’”

John is opening up exclusively to PEOPLE ahead of the upcoming Netflix docuseries Cold Case: Who Killed JonBenét Ramsey?, streaming Monday November 25.

The three-part series takes a fresh look at the murder case, which began when John found his young daughter dead in a dusty basement room in their upscale neighborhood.

John and his late wife Patsy also found a threatening handwritten ransom note in their home, believed to have been left by the killer.

But the dead girl’s parents soon became suspects in the assault and murder of their daughter, who died from strangulation and a blow to the skull.

Netflix’s three-part docuseries takes an in-depth look at what John sees as missteps made by authorities investigating JonBenét’s murder, amid an international media frenzy that only made matters worse.

He says he’s speaking out in part to encourage someone to come forward with new information and to “put pressure” on police to use advances in DNA technology and genetic genealogy to finally catch JonBenet’s killer to get.

For more about John Ramsey’s fight to see JonBenét’s murder solved in his lifetime, subscribe to PEOPLE now or pick up the new issue of People, on newsstands next week.

When John spoke to PEOPLE, he expressed his shock at learning that the unidentified 12-year-old girl was allegedly raped in the middle of the night, two miles from where the Ramseys lived — and that she went to the same dance studio as JonBenét. .

“I think the process was exactly the same,” he tells PEOPLE. “I believe the killer was in the house when we got home and was waiting for us to go to sleep.”

In the case of the 12-year-old girl and her family, “they came home, set the burglar alarm and the killer was already in the house. A very similar method, and yet the police called it off. It was the same investigator on our case,” John says.

“But even the little girl’s father said, ‘On a scale of one to 10, I give the police a minus five.’ It was just… stupid ignorance. But yeah, I think it was very possibly the same person.”

John, Patricia and Burke were never charged in connection with JonBenét’s murder. Patsy died in 2006.

The three-part Netflix docuseries Cold Case: Who Killed JonBenét Ramsey? starts streaming Monday November 25.